Telephone ringing apparatus with vibratory reed of magnetic material



Oct. 3, 1950 J. M. BLACKHALL ETAL 2,524,510

TELEPHONE RINGING APPARATUS WITH VIBRATORY maar;r oF MAGNETIC MATERIAL Filed Marchv 5, 1947 v 2 Sheets-Sheet oct, 3, 195o J. M. BLACKHALL E-rAL 2,524,510 TELEPHONE RINGING APPARATUS WITH VIBRATORY REED oF MAGNETIC MATERIAL Filed March 5, 1947 2 Sheets-Sheet 2 atented ct. 3, 1,956

UNITED STATES PATENT oFFIcE4 TELEPHONE RINGI'NG APPARATUS WITH VIBRATORY REED-l oF MAGNETIC MATE-- RIAL James Blackhal'i ana- Franklrin J. Hickman,v Galion, Ohio,l ass'g'nrs to The North' Electric Manufacturing Company, Galion, Ohio; a cor;

poration of Ohio Application March 5,1947, Serial N o. 732,458`

I C1. ms?) 1ov claims.

This invention relates, generally, to telephone ringing apparatus, and it has particular relation to' vibrator type of ringing devices by rne'ansfo'fy which direct current is caused to no'w inter'- mittently through the primary7 Winding of a transformer for causing alternating current to' now in the secondary winding thereof a't a' frequency which is determined by the frequency of vibration of the ringing device'. Y

Among the objects of this invention are: To increase the efficiency of the magnetic' circuit' of ringing devices of the vibrator type; to employ' magnetic material' for the vibrator" reed thereby' requiring only one driving coil and' avoiding" the use of an independent armature; to anchor one end of the reed' to" one of the pole pieces' making up the magnetic circuit so' that in vibrating' it' nexes relative thereto; t'o' employ' a'n' air' gap' the magnetic circuit bridged by the ree'd' that' is" relatively short as compared' to the length of the" magnetic circuit; to adjust the length of the magnetic circuit; to provide' forv varying' the frequency of Vibration of the reed';` and to'a'djlst the reedas'sernbly' so that it' will vibrate at the' desired' frequency. n

Other objects of' this invention' will, in' part', be' obvious and in part appear hereinafter.A

Accordingly, this invention' is diselo'se'd in` the embodiment thereof Ashcwnv in the' accompanying- Figure 1 is a view, inside elevation, of` the ringing" device sli'own Figure" 2, one o'f the" contact' brackets being broken away' in order' t'o' illustrate more clearly certain details' of construction;

Figure `2'i's a View', in front elevation', of` the' ringing' device;

Figure 3 isa topplan vi'ew' of the ringing'device shown in' Figurez'; v

Figur'e 4v' isa detail sectional' view;v at an'A en'- larged scale", taken along the line`4l-4'of'Fig're' 2f and Figure `5 illustrates; ,diagrammaticallv the'` electric c'ircllilfconnectionsv that can employed' in the use of the ringing device shownin Figures" l through 4 and described in detailhereinafte'. Referring now particularly to Figures l, 2, 3`

and 4 of the drawings, it' will be observed that the reference character' IIlfdesignate'sv a base plate K' which is formed of non-magnetic material, such as brass.V The base platel I'' may be' formed from" plate' stock having a thickness of 1/2" inch, a'

width' of ll/z inches, and a length of 4%4` inches.' y

Themagn'etic circuit for the' ringing deviceli's located at the upper right-hand' corner oftheL base plate I0 as viewed in Figure 2. The'r'nag--" netic circuit includes an upper pole piece' I l that' is generally L-shaped' and4 preferablyiis formed of annealed cold rolled steel. The pole piece I"I may be secured nat against the surface of thej base" plate I'Il by countersunk screws I2 and IS* that extend from the opposite side into the pole- The'stock making up'the pole piece IIV piece II. preferably has a thickness of 7A; inch. The short ari'n I4 of the pole piece IIAmay be 11A inches74V long, while the longer'arm I5 may be 23-1f inches* long. The arms" I4'and I5 each may have ai width of inch. The lower portion of thel outer surface of the longer arm` I5 is recessed; asr` indicated at I6, about .025 inch from the lower end to a point midway thereof fo'r a'- purpose which willv be apparent presently. The lower" end I1 of the longer arm I5'may have a width' of alf inch and then, as indicated at I8', the lower' Y surface may be cut away' at an angle' of 45v degrees.

The magnetic circuit also includes a lower.

pole piece that isindicated, generally,l at which has an angular configuration and is formed of annealed cold rolled magnetic iron. The.`

lower pole piece I9 has oner side 20 which is held nat against the upper surfaceof the base plate I0` by a lscrew 2| that extends through an elongated` opening 22 in the side 20. The purpose of the" elongated opening 22 is to permit adjustment o1?r the lower pole piece I9 in a direction at right angles to the longer arm I5 of the I shapedupper pole piece II.

1/31 inch and the side 20 may have a width Y of 5/5 inch and a length of 111.;` inches. The other side 23 of theflowerpole piecev I 9 extends at rightv angles to the side 20 `and has a width of '7/8 inch'L which' is the same` as'" the thickness of the upper*- pole' piece II. It has an overall length of 1&2' inches, As shown more clearly in Figure 4, the: side`23 of the lower pole piece I9' has an elongated" slot 24' through which' a screw' 25' prejects" into' a'core 260i magnetic'inaterial. The slotted open'- The lower pole piece vI9 Ais pref-gL erably formed of stool; having a thickness of;-

3 ing 24 is provided to permit adjustment of the lower pole piece I9 in the manner described herenbefore.

As indicated the core 26 is formed of magnetic material. It may be formed from cold drawn magnetic iron rod and it may have a diameter of inch. It has a length of 178 inches and extends between the opposed faces of the side 23 of the lower pole piece I9 and of the shorter arm I4 of the upper pole piece Il. A screw 21 extends through the arm I4 into the upper end of the core 26 for securely holding the same in place. An energizing winding or coil 28 is located on the core 26 and, as will be described hereinafter, it serves to energize the magnetic circuit described for operating the ringing device.

As shown more clearly in Figures 2 and 4 of the drawings, the side 23 of the lower pole piece I9 has an extension 29, the ends 30 of which are cut ol at approximately 45 degrees for concentrating the flux in the magnetic circuit llowing to or from the short width tip I1 of the arm I5 that forms a part of the upper pole piece II. This magnetic flux, in part, flows across an air gap 3l between the extension 29 and the tip I1, and it has a fixed length which is relatively short as compared to the length of the magnetic circuit or more particularly to the length of the longer arm I5 of the upper pole piece II. For example, the air gap 3l may have a length of a inch. Satisfactory results are obtained using this length of air gap when the other proportions of the magnetic circuit are as specified.

Now it will be observed that the upper pole piece II, the lower pole piece I9 and the core 26 form a generally rectangular magnetic circuit having an air gap 3l in one side thereof the length of which is relatively short as compared to the entire length of the magnetic circuit. Because of the relatively short length of the air gap 3I as compared to the length of the magnetic circuit, its efficiency is increased, leakage flux is reduced, and less power is required for energizing the coil 28 to obtain satisfactory operation of the ringing device.

The moving part of the ringing device comprises a reed 32 that may be formed of annealed spring steel, tempered to the desired hardness, and it may be secured by screws 33 to the upper end of the longer arm I5 of the upper pole piece II, as illustrated more clearly in Figures 1 and 2 of the drawings. rIhe reed 32 may have a length of six inches, a width of 5/8 inch and may have a thickness of either .049 or .083 inch, depending upon the frequency of vibration as will be described in more detail hereinafter. Since the reed 32 is fixed to the upper pole piece II, it flexes relative thereto, and it is to permit this action that the longer arm I5 is recessed as indicated at I6. The reed 32 extends along the arm I5 over the recessed surface I6 and in overlapping relation past the air gap 3l. Since the reed 32 is formed of magnetic material, it is unnecessary to provide a separate armature for cooperating with the upper and lower pole pieces II and I9 to attract the same thereto on energization of the coil 28. The reed 32 cooperates with the upper and lower pole pieces II and I9 to form variable length upper and lower air gaps 3Ia and 3Ib disposed above and below the fixed length air gap 3I and in shunting relation thereto. The aggregate length of these upper and lower variable length air gaps 3 Ia and 3Ib is less than the length of the xed air gap 3l.

On opposite sides of the reed 32 power contact springs 34 are located and spaced therefrom by metal spacers 35. The contact springs 34 are reenforced by power contact spring supports 36 which, as indicated in Figure l, have their lower portions recessed as indicated at 31 so as not to interfere with the movement of contacts 38 that are carried by the power contact springs 34 near their lower ends. The contacts 38 may have a diameter of it inch and be formed of tungsten with a nickel backing. They may be secured, as by welding, to the power contact springs 34. The contacts 38 are arranged to engage contacts 39, of tungsten or the like, that are carried at the inner ends of contact screws 49 which are threaded in power contact screw brackets 4I that are suitably insulated from opposite sides of the base plate IIJ and secured thereto by screws 44, as illustrated. Connection to the screws 40 may be had by terminal strips 45 to which conductors can be secured as by soldering, as will be readily understood.

The reed 32 also carries a motor contact spring 46 that is spaced from the left-hand power contact spring support 36 by insulating spacers 41. The motor contact spring 46 is reenforced by a motor contact spring support 48 and it carries a contact 49, similar to the contacts 38, for engaging the contact 50, similar to the contact 39, that is carried at the inner end of a motor contact screw 5I which is threaded in a. bracket 52 that is suitably insulated from the base plate I0 and secured thereto by screws 55. Connection to the contact screw 5I may be had by a terminal strip 56. The motor contact spring support 48 has an extension 51' to which connection can be made to one terminal of the coil 28. This extension 51' carries the point of connection back to the point of least vibration, thus reducing to a minimum the vibration on the connecting wire.

It will be observed that the power contact springs 34 and the associated power contact spring supports 36 together with the motor contact spring 46 and its associated motor contact spring support 48 are mounted on the reed 32 for movement therewith just below the air gap 3l. They are securely clamped in place on opposite sides of the reed 32 by screws 51 which extend therethrough, as indicated in Figure 4, and are threaded into a plate 58. An insulating sleeve 59 extends over the shank of each of the screws 51 for the purpose of insulating the motor contact spring 46 and the motor contact spring support 48 therefrom. The power contact springs 34 are in circuit with the reed 32 so that it is unnecessary to insulate them therefrom. Connection thereto can be made merely by making a, connection to the base plate I0.

As indicated hereinbefore, the frequency of vibration of the reed 32 is determined, in part, by its thickness. Another factor that is involved in determining the frequency of its vibration is the mass of the weight that is located at its lower end. For this purpose, discs 62 may be secured eccentrically as by a screw 63 to the lower end of the reed 32. As shown, the discsl 62 are round and may be formed of metal, such as brass. Each disc may be provided with a punched out projection 64 for cooperating with a similarly shaped recess 65 in an adjacent disc 62 for keeping them in proper register. As will appear, hereinafter, more than one disc 62 may be located on each side of the reed 32 to provide different frequencies of vibration. It is when they are thus juxtaposed that' the projections M and recessesl 851 function-- tomaintain the required alignment.

Since the discs 62 are positioned eccentrically on the lower endofthe reed 32, it is possible to shift them from one position; to another, as illustrated by the broken outline thereof` in Figure 1,

so as to provide a fine adjustment ofthe frequency of vibration of thereed 32. For purposes of illustration, it is pointed out that eachY of the discs 62 may have a diameter of inch. andla thickness of T15. inch. y

'I'heringing deviceillustrated in Figures 1, 2, 3l and 4 and described hereinbefore can be used, with suitable modifications, for generatingV ringing frequencies ranging from 16% cycles per sec-- ond to 66% cycles per second. Forfeachfrequency a separate ringing device is providedwith an` Cycles per Numberot Second Discs 16% 22 2J 16, 25 8 30' 5 S31/, 4'. 42 10 50' 6 54 6l esas 2.

The ringing device shown in the drawings and' described hereinbefore is preferably mountedv in an upright position on asuitable frame or panel. For this purpose mounting openings,l 66 may be provided at opposite corners of :the base plate I as illustrated.

In Figure of theV drawings, the ringing device', as previously describedg' is illustrated generally at 10. In this gure are illustrated' the circuit connections that canv beemployed for using thisv device. Itv will be notedthat a battery 1| is employed and this may be the common battery of a telephone system which may have` a normal voltage of 48 volts.

"When motor contacts-40 and' 50 arerengaged, the coil 28 is connected across the-48 volt battery 1I and thereed 3'2fis attracted to separate these contacts., The energizing circuit for the coil 28 is then broken and the reed 32swlngs or flexes inthe opposite direction to again causel these contacts to engage. As described hereinbefore, the frequency of movement of the reed 32'isdetermined `by its thickness and the-number ofl discs 62 located on the lowerend thereof.

kThe movement of the reed* 32 concurrently causes the power contacts 39 on opposite sides thereof to be engaged and, sinceY the reed` 32 is connected to the midpoint of the 48 volt battery 1l, a voltage of 24 volts is applied across primary windings 12 and 13 of a transformer that is indicated, generally, at 14. This voltage is applied alternately to the primary windings 12 and 13 so that current ows therein during these periods in the directions indicated by the arrows 16 and 11. As a result an alternating current is induced in a secondary winding 18, which as shown may be connected to the output or ringing circuit represented by conductors 80 of. the telephone ex- 6 change. 'I'hese conductors 8i)y can be connected inknown manner to a subscriber's clrcuit'forringing the bells of one or more telephone sets connected thereto. Different frequencies are employed for ringing diiferent` parties onv the same line and it is for this purpose* that the ringing device is constructed so that essentially the same parts can be employed' for different devices to generate different ringingfrequencies.

In order to prevent the ringing frequency from being applied to the central or common batteryK 1|` suitable filter means can be provided between the ringing device 10 andthe battery 1|. Forv example, inductors 83 maybe provided in series circuit relation with the conductors tothe batteryv1| and capacitors 84 may be connected thereacross as illustrated. An inductor 85 and a capacitor 86 may be connected across thel conductors 80 to reduce sparking ofthe power contacts 38-39.

In order to provide a clear and complete disclosure of the invention, various dimensions have been specified and materials mentioned. It will be understood that some variation in these specifications can be made without departing from the spirit and scope ofthis invention. Accordingly, it is intended that all matter shown in the accompanying drawingsand described hereinbefore shall be interpretedl asv illustrative and not in a limiting sense.

What is claimed as newis:

l. In telephone ringing apparatus, in combination, a base plate of non-magnetic material, an upper L-shaped pole piece of magnetic material secured flat on said base plate having the lower surface of the longer arm recessedfrom the outer" end to about midwayof its length, a lower angular pole piece of magnetic material having oneside secured to said base plate and the other side disposed parallel to the shorter arm of said upper pole piece and spaced from said outer end of said longer arm thereof to form a xed length air gap therebetween, a magnetic core extending between said short arm of said upper pole piece.

and said other sideof said' lower pole piece and secured thereto, a coil on said core, a reed in the;

form of a flat strip of spring magneticmaterial secured at one endto the upper'end of said longer arm of said upper pole piece and extending. over r `*said recessed outer surface thereof and said ixedi` length air gap for a substantial distance beyond` the same, said reedcoacting with said upper andi lower pole pieces to form upper and lower variable length air gaps extending in shunting relation to fsaid xed'length air gap, the aggregate length of said upper and lower variable length air gaps being less than the length of the xed length air gap, motor contact means operated by said reedv for intermittently opening and closing an ener'- gizing circuitfor said coil tovibrate said reed, and power contact means operated by said reed to close and open av telephone ringing circuit.

2. The invention, as set forth inclaim 1,

wherein thelengtnof the fixed length air gap is',

relatively short as compared to the length of the longer arm of the upper pole piece.

3. The invention, as set forth in claim 2, wherein the motor contact means includes a stationary contact carried by the base plate and a cooperating movable contact spring supported by the reed, and the power contact means includes a pair of stationary contacts carried by said base plate on opposite sides of said reed and a pair of cooperating movable contacts spring supported` by said reed on opposite sides thereof.

4. he invention, as set forth in claim 3, wherein the spring supports for the movable motor and power contacts are fastened to the reed adjacent the air gaps and they extend away therefrom along said reed.

5. The invention, as set forth in claim 4, wherein weight means for adjusting frequency of vibration is provided at the other end of the reed, which frequency of vibration is determined by the thickness and the mass of said weight means.

6. The invention, as set forth in claim 1, wherein weight means in the form of one or more metallic discs is provided at the other end of the reed and eccentrically mounted thereon and the frequency of vibration thereof is determined by its thickness, the number of said discs and the position thereof relative to said reed.

7. The invention, as set forth in claim 1, wherein the lower pole piece is adjustable in a direction of right angles to the longer arm of the upper pole piece for varying the length of the lower variable length air gap.

8. In telephone ringing apparatus, the combination of a magnetic core, a coil on said core, a first pole piece extending from one end of said core, a second pole piece extending from the other end of said core. adjacent ends of said pole pieces establishing a iixed length air gap therebetween adapted to be threaded by iiux lines, a magnetic reed extending substantially parallel to the path of the flux lines threading said iixed length air gap, said reed being spaced slightly from said ends of both pole pieces to establish a rst variable length air gap between said iirst pole piece and said reed and to establish a second variable length air gap between said second pole piece and said reed, said two Variable length air gaps `being connected magnetically in series through .said reed and creating a second flux path in shunt :of the flux path through said fixed length air gap, motor contact means operated by said reed for intermittently opening and closing an energizing circuit for said coil to vibrate said reed, and power Contact means operated by said reed to close and open a telephone ringing circuit,

9. In telephone ringing apparatus, the combination of a magnetic core, a single coil on said core, a first pole piece extending from one end of said core, a second pole piece extending from the other end of said core, the adjacent ends of said pole pieces establishing a fixed length air gap therebetween adapted to be threaded by iiux lines, a reed in the form of a flat strip of spring magnetic material secured at one end to one of said pole pieces and extending substantially parallel to the path of the ux lines threading said ixed length air gap, the free portion of said reed being spaced slightly1 from said ends of both pole pieces to establish a first variable length air gap between said first pole piece and said reed and to establish a second variable length aii` gap between said second pole piece and said reed, said two variable length air gaps being connected magnetically in series through said reed and creatingx a second iiux path in shunt of the iiux path through said iixed length air gap, the aggregate lengths offsaid two variable length air gaps being less than the length of said fixed length air gap, means for adjusting the position of one of said pole pieces relatively to the other so as to adjust one of said air gaps, motor contact means operated by said reed for intermittently opening and closing an energizing circuit i or said coil to vibrate said reed, and power contact means operated by said reed to close and open a telephone ringing circuit.

l0. In telephone ringing apparatus of the class described, the combination of a magnetic core. a single energizing coil on said core, an upper pole piece extending from the upper end of said core, a lower pole piece extending from the lower end of said core, the adjacent ends of said pole pieces establishing a iixed length air gap therebetween adapted to be threaded by flux lines on said core, a reed in the form of a at strip of spring magnetic material having its upper end secured to said upper pole piece and extending downwardly substantially parallel to the path of the iiux lines threading said fixed length air gap, the free portion of said reed being spaced slightly from said ends of both pole pieces to establish an upper variable length air gap between said upper pole piece and said reed and to establish a lower variable length air gap between said lower pole piece and said reed, said two variable length air gaps being connected magnetically in series through said reed and creating a second iiux path in shunt of the iiux path through said iixed length air gap, adjustable mounting means for said lower pole piece enabling the latter to be shifted to adjust the length of said lower variable lengthair gap, motor contact means operated by said reed for intermittently opening and closing an energizing circuit for said coil to vibrate said reed, a pair of contact springs mounted on opposite sides of the swinging end of said reed, and cooperating relatively stationary contacts adapted to be engaged by said contact springs for closing and opening a telephone ringing circuit.

JAMES M. BLACKHALL. FRANKLIN J. HICKMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Certificate of Correction Patent No. 2,524,510 October 3, 1950 JAMES M. BLACKHALL ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 35, for the Word lower read outer; line 36, for outer read lower;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office. Signed and sealed this 2nd day of January, A. D. 1951.

THOMAS F. MURPHY,

Assistant ommz'ssz'oner of Patents.

Certificate of Correction Patent No. 2,524,510 October 3, 1950 JAMES M. BLACKHALL ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 35, for the Word lower read outer; line 36, for outer read lower;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office. Signed and sealed this 2nd day of January, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gommzssz'oner of Patents. 

